Table 50: Impact of slip on service types
Service Potential Impact
Encrypted Text Encryption key must be resent.
Video Freeze frame for several seconds. Loud pop on
audio.
Digital Data Deletion or repetition of Data. Possible Misframe.
Facsimile Deletion of 4-8 scan lines. Drop Call.
Voice Band Data Transmission Errors for 0.01 to 2 s. Drop Call.
Voice Possible Click.
Types of synchronization
Clock synchronization can be either tracking on the primary or secondary reference clock or
free run (non-tracking). In LD 73 (prompts PREF and SREF), the DTI/PRI which supports the
clock controller daughterboard is defined as the primary clock reference.
Another DTI/PRI may be defined as the secondary clock reference.
The clock controller
synchronizes from the primary or secondary's incoming pulse stream. The clock controller
supplies clocking to all the other DTI/PRI loops.
DTI/PRI hardware detects frame slips in tracking and free-run modes. For tracking mode,
running the midnight routines prints the number of overflows and clears the counter. For free-
run mode, running the midnight routines prints the number of frame deletions and repetitions
and clears the counters.
Tracking mode There are two thresholds set in LD 73 the SRTK prompt. Refer to the description
in LD 73. Also see
Figure 21: Frame slip tracking thresholds on page
115.
Table 51: LD 73 - SRTK prompt
Prompt Response Description
SRTK 1-(5)-24 1-(30)-3600 Slip rate maintenance (in hours) and out-of-service
threshold (per hour).
These are the frame slip rate thresholds for the
tracking mode. The first value is the maintenance
threshold; the elapsed time (in hours) in which 2 frame
slips occur (default is two slips in five hours). The
second value is the out-of-service threshold; or the
number of slips allowed in one hour (default is 30 slips
in 1 hour).
When a threshold is reached, a DTA messages is
output as follows:
DTA015:Frame slip — tracking — maintenance limit.
DTA016:Frame slip — tracking — out of service limit.
1.5 Mb DTI/PRI maintenance
114 ISDN Primary Rate Interface Maintenance November 2011
Comments? infodev@avaya.com
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